1. Field of the Invention
The present invention generally relates to a width adjusting device adapted for a rotary lithographic press which is equipped with a plurality of printing sections. More particularly, the present invention relates to an improved width adjusting device which adjusts the width of the paper web printed by at least the first printing section.
2. Description of the Related Art
In commonly used rotary lithographic printing systems employing dampening water, a paper web is supplied with such dampening water when the paper web is passed through a printing section. Since most of the pulp fibers of the paper web are orientated in the longitudinal direction of the paper web, the pulp fibers are expanded laterally due to the dampening water. As a result, the paper web will be remarkably extended in its width direction after the printing section.
A typical rotary lithographic printing system TP as shown in FIG. 10 includes vertically arranged printing sections, so that the former printed image and lines by the preceding printing section and the later printed image and line by the succeeding printing section are often sheared owing to the swell of the paper web W. Accordingly, this will produce printed materials with poor quality.
Therefore, the inventor of this application has submitted two inventions as Japanese Patent Application No. 3-357580/1992 and 4-309476/1992 to prevent the printed images from shearing. These inventions disclose similar systems to apply any pressure onto a running paper web and form wave in the lateral direction of the paper web. The lateral wave may cancel the extended dimension in the lateral direction of the paper web. Such wave forming devices are arranged between the preceding and succeeding printing sections so as to fit the image and lines printed by the preceding printing section with that by the succeeding printing section.
However, since the wave forming devices employ contact members such as roller, knaggy rod, and the like to apply the contact pressure onto the web surface, such contact members may cause the printing quality of the printed image to be poor. In detail, when the contact members are moved (rotated) at the same speed of the paper web, printing ink and paper dusts are stored on the contact surface of the contact members. The stored ink and paper dusts may cause various damages in printed images, blanket cylinders, plate cylinders, and inking systems. On the other hand, when the contact members are stationarily arranged, printing ink and paper dusts are remained and stored in the downstream area of the contact members. The stored ink and paper dusts may gradually grow longer in the paper running direction, and finally cause various troubles in the printing plate, blanket cylinder and inking system of this printing apparatus resulting in spoiling printed matters.